杭州湾内台风浪模拟研究

杭州湾自然地理条件特殊、社会经济发达,研究杭州湾内台风浪特征对该地区的防灾减灾具有重要的现实意义.现选用藤田台风模型模拟台风场,采用基于动谱能量平衡方程的SWAN模型模拟台风浪,计算了台风Winnie过程中杭州湾内的波浪情况.通过分析台风过程中不同时刻杭州湾内波高分布图,得到波高的空间分布变化规律;并将波高数据进行回归分析,得到了杭州湾内波高与风速和水深的相关关系.     

“达维”台风作用下连云港海域台风浪数值模拟

为准确模拟"达维"台风过境期间连云港海域波浪场分布,采用Jelesnianski风场模式模拟的海面10m风速作为波浪模式MIKE-SW的驱动风场,再现1210号"达维"台风登陆连云港海域波浪变化过程。模拟计算结果表明,Jelesnianski风场模式成功复演了"达维"台风过境期间风动力变化过程,1210号"达维"台风与1209号"苏拉"台风形成明显的双台风效应;"达维"台风风暴潮期间,连云港海洋站最大风暴增水1.78m,连云港海域风暴增水现象十分明显;利用三重网格嵌套技术,考虑实时风暴潮增水效应的台风浪模型能够较好地模拟连云港近海波浪成长过程,台风过境期间徐圩海洋站处H1/3波高最大值为3.86m,近岸海域波高等值线分布较为密集,分布趋势与水下地形等深线基本一致,破波带以内水域衰减速度明显加快,与连云港海域属于淤泥质海岸类型的性质相吻合。     

施工期台风浪作用下沉箱碰撞破坏分析

以“莎莉嘉”台风引起施工期沉箱碰撞破坏为背景,研究台风浪作用下施工期沉箱碰撞破坏模式及机理。提出基于台风浪作用下沉箱碰撞反应分析两步走的数值模拟方法,该方法利用高精度流体模拟软件Flow-3D的造波技术模拟台风引起的波浪传播过程,并与沉箱结构作用获取沉箱波浪力时程曲线;建立沉箱精细化有限元模型,将上述波浪力时程曲线施加于沉箱结构,利用LS-DYNA显式求解器分析沉箱结构的碰撞反应。应用该方法对“莎莉嘉”台风引起施工期沉箱碰撞破坏进行分析,结果表明:数值模拟的沉箱结构在不同波浪方向作用下发生不同角度的碰撞会导致不同的沉箱碰撞破坏模式,波浪作用方向与沉箱前后壁夹角为60°时,沉箱碰撞破坏模式与“莎莉嘉”台风作用期间的现场情况吻合较好。     

东中国海至长江口海域台风浪特性的数值模拟研究

东中国海至长江口的台风浪用两个海浪数值模型来模拟:适用于海岸、河口及湖泊水域的SWAN模型,将其嵌套于东中国海范围内的WAVEWATCHⅢ(WW3)模型.8114号强台风在长江口产生了巨大波浪,所以文中选其为例.将WW3应用于东中国海计算区域,模拟大范围的波浪,为高分辨率的长江口水域SWAN模型提供二维波谱动态边界条件.Takahashi风模型用来模拟东中国海(3小时一次)和长江口(1小时一次)的风场.对东中国海台风浪的模拟结果表明:最大的台风浪出现在风暴路径的右侧,且发生在长江口深水开敞东边界.在台风到达长江口之前,和风成波相比,涌浪占主导地位.台风到达长江口时,风成波和涌浪并存.波向主要受涌浪方向和复杂的地形影响.     

SWAN模型在围头湾外海设计波浪要素推算中的应用

传统的设计波浪推算方法不适用于长期波浪观测数据匮乏的海域，近年来，波浪数值模拟方法成为推算设计波浪的重要手段。该文基于近岸波浪传播模型SWAN和参数化台风风场模型建立台湾海峡台风浪数学模型，利用201808号台风“玛利亚”影响台湾海峡期间的风速和波高观测资料检验模型合理性，通过数值模拟1996-2015年共92场影响台湾海峡的热带气旋过程波浪场计算围头湾外海E、ESE、SE、SSE向的年极值波浪要素。在此基础上利用P-Ⅲ型曲线拟合20年的年极值波高和周期，获得围头湾湾口(40 m等深线处)E、ESE、SE、SSE向各重现期的设计波浪要素。研究成果可为围头湾海域海岸工程的规划和设计提供参考。     

基于Holland风场的台风浪数值计算

在海岸工程中,台风浪的影响较大。为了提高台风风场模拟精度,基于Holland台风风场模型,选取不同的最大风速半径参数和B参数进行组合,将模型构造风场与实测浮标风速资料进行比较分析,误差统计表明,Willoughby风速半径公式和Vickery的Holland B参数公式组合之后的计算误差最小,对风场的模拟效果最好。然后采用SWAN近岸波浪模型,选取最优风场参数,模拟了1323号“菲特”台风过境期间浙南地区的台风浪。模拟结果表明,最优组合参数生成的台风风场,对台风浪的模拟结果较好。当台风登陆时,温州地区的有效波高超过了10 m,明显高于其他区域,近岸波高等值线分布较为密集,台风移动方向右侧有效波高相对较大。台风进入内陆以后,波高迅速减小至4 m左右。     

强涌浪海域海塘防护的技术实践

浙江沿海岛屿分布广泛,在开敞式多岛屿的海域中,波浪与多岛屿的相互作用是一个相当复杂的物理过程,地形复杂且同时受风浪和涌浪的作用,势必会影响波浪场的分布,在强涌浪海域进行工程结构保护也是工程亟需要解决的问题。以强涌浪海域的海塘工程(栲门大坝)为典型工程,利用MIKE21谱波浪(SW)模型对复杂地形的波浪场进行计算分析,对强涌浪海域提出工程防护措施。     

气旋生浪的数值模拟研究及其特征分析

利用Holland模型、Jelesnianski模型构造飓风风场,并针对快速移行气旋其风场不对称性明显的特征构造一种基于实测数据的风场,驱动第三代海浪模式WAVE WATCHⅢ,对飓风Juan影响下北大西洋的海浪进行数值模拟。通过对比试验结果与观测数据的误差,比较3种方法对于合成高速移行飓风风场的适用性,并选择最优模拟结果对海浪组成特征进行分析。结果表明:基于实测数据的合成风场与真实风场最接近,海浪模拟效果最优;飓风中心海域有大片的风浪大值区,风浪4 m波高等值线内基本无涌浪,涌浪主要分布在风浪大值区外围左侧海域;风浪波高比涌浪波高大,涌浪影响范围广。     

台风作用下伶仃洋波浪场的模拟计算

该文运用SWAN模型对“0814”号台风作用下伶仃洋的波浪场进行了模拟研究.计算得到从台风登陆6小时前开始至登陆6小时后的南海北部海域波浪场,并作为伶仃洋海域波浪的外边界条件.在计算珠江河口伶仃洋局部海域的波浪场时,相比之下伶仃洋海域只是一个局部小区域,故风场采用随时间变化的均匀风场.先不考虑流的影响,水位采用伶仃洋内部代表点南沙站的水位并忽略水位伶仃洋内的变化,模拟计算时全面考虑风输入项、白帽作用、底摩擦作用、破波作用、耗散作用以及三波相互作用和四波相互作用.计算结果表明,在台风登陆过程中,南海北部和伶仃洋波浪场的变化基本依赖台风风场变化,并在台风登陆时波高达到最大,波浪的传播方向与风向基本一致.最后,还考虑了在台风登陆时刻加入流场和水位场,以此分析了流场对波浪场结果的影响.     

三门湾下洋涂围垦工程堤前波浪要素分析

分析了三门湾下洋涂海区的海域特征,采用波浪折射和绕射数值模拟,表明下洋涂的西南围区受外海混合浪的影响较大。为此,采用风浪生成模型摸拟了局部海域的风浪,结果与实测结果较为一致。从而建议下洋涂围区的设计波要素取值外海浪和局部风浪共同作用段,采用H=!H12 H22计算堤前合成浪的波高。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.